New β Cep pulsators discovered with K2 space photometry

Abstract

We present the discovery of three new β Cep pulsators, three new pulsators with frequency groupings, and frequency patterns in a B3Ib star, all of which show pulsations with frequencies as high as about 17 d −1 , with K2 space mission photometry. Based on a Fourier analysis and iterative pre-whitening we present a classification and evaluate the potential for asteroseismic modelling. We include the lists of pulsation frequencies for three new β Cep pulsators, CD-28 12286, CD-27 10876, LS 3978, and additional pulsation mode frequencies for the known β Cep pulsator HD 164741. In addition we characterise the regular frequency spacing found in the new pulsator HD 169173, and discuss its origin. We place the newly discovered variables in a colour-magnitude diagram using parallaxes from Gaia-DR2, showcasing their approximate location in the massive star domain. The identified frequency lists of these multiperiodic pulsators are a good starting point for future forward seismic modelling, after identification of at least one pulsation frequency from high-resolution time series spectroscopy and/or multi-colour photometry.

Probing the interior physics of stars through asteroseismology

“…In the case of the δ Sct stars, lack of mode identification prevents applications, although managed to overcome this hurdle for a limited sample of such stars. The few observed β Cep stars with precise space photometry either lack mode identification (Burssens et al, 2019) or rotate slow enough to stick to the first-order perturbative approach. Suárez et al (2010) made a careful analysis of second-order effects in Ω for stochastic p modes and found those to become important for equatorial rotation velocities above some 15 km s −1 .…”

Asteroseismology of High-Mass Stars: New Insights of Stellar Interiors With Space Telescopes

“…The K2 mission allowed the rotation, pulsation, and binary properties of the seven sisters of the Pleiades to be studied in detail for the first time thanks to its long time base and high precision (White et al, 2017). Since the end of the K2 mission in 2018, these high-precision data have revealed dozens of previously unknown β Cep and SPB stars (Pope et al, 2016(Pope et al, , 2019bBurssens et al, 2019) and ubiquitous stochastic low-frequency variability in the photospheres of massive stars (Bowman et al, 2019b).…”

Fully compressible simulations of waves and core convection in main-sequence stars

“…On the upper main sequence, stars with spectral types O and B (M > 3 M ) observed in µmag precision space photometry show coherent opacity-driven p-or g-modes as well as stochastic variability caused by internal gravity waves. This occurs in slowly pulsating B (SPB) stars with masses between 3 M and 9 M (Pápics et al 2017;Bowman et al 2019a;Pedersen 2020), in β Cep stars with masses between 8 M and 25 M (Briquet et al 2011;Burssens et al 2019) A&A proofs: manuscript no. igw (Buysschaert et al 2015;Bowman et al 2019b;Pedersen et al 2019;Bowman et al 2020).…”